Screw propeller for use upon aircraft



May l0, 1932. H. suKoHL 1,857,678

SCREW PROPELLE FOR USE UPON AIRCRAFT Filed April 17, 1950 'g. 7 fig. 2

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, .Im/entor':

Hita/ wey maar yPaterxtecl`-May 10, 1932 UNITED. sTATSf- PATENT* OFFICE namnrcn'suxom.; or BERLIN-WAI'DMANNSLUST. GERMANY scnnwrnormmn Fon Usl: UPON imam My invention relates to improvements inf screw propellers for use upon aircraft and more particularl in screw ropellers in 7which the propel er blades ma e froni wood are clamped within the hub,'the said hub being made in two sections clamped together. and on the inner ends of the blades by means of screw bolts or the like. .As no w constructcd the propeller blades termi/nate l at e 10 their inner ends in conical journals or shafts engaging in corresponding bores of the hub. In the operation of the propeller the saidconical journals or shaftsact as wedgeswith in the sectional hub tending'to force the -sections apart, and by reason of the high centrifugal force of the blades the strain exerted on the hubI and the members connecting the sections thereof is high, so that strong and heavy. hubs and connecting 'members are j needed. The object of the improvements is force is-obviated, andthe said centrifugal force is taken up by the transverse annular shoulders ofthe shafts or journals and the *'correspondingshoulders formed in the tapering recesses of the. hub. `By thus con' structing the shafts or journals and the hubs.

also the compression of the said. shafts oi' journals caused by the wedging action is ob viated, so that the blades are rigidly held within the hub for anylength of time.

For the purpose of explaining the `inven tion an example cmbodyingthe samev has been shown in the accompanyaing drawings, in which the saule letters of reference have .been used in all the views to indicate corresponding parts. In said drawings,

Fig. 1 is an elevation'showing the propch ler, one of the sectionsfof th'e hub being lrcmovcd for more clearly'. showing the shape of the shafts or journals ofthe blades,

Application tiledA April 17, 1930,8eria1 No. 444,98d6, and in Germany April 92,l 1929,

Fig. 2 is a sectional elevation `taken on the line 2f-2 of Fig. 1, and

.F ig. 3 is an elevation showingthe hub.

In the construction shown vin'. the figures the hub of the propeller is divided` transI vcrsely of the-pro Teller shaft into two secs tions a and b slight y spaced from each other,

asis shown at o, and adapted tov be clamped `towards each other `by screwI bolts m and n, a cap p being laced on the section band ixod -in position by means of the said bolts. The hub sections are provided,.with gli-gnedbores il: by means-of which they are xed to the propeller shaft. At op osite sides of the said bore the hub is formey with tapering lrecesses adapted ta receive the journals or shafts aand f of theblades g and h. As

shown the said journals or shaftse and ftas,

per inwardly from their outer 'ends towardsthe body of the blades, and they are composed of a plurality of cylindrical portions c and d which are successively reduced in diameter thus roviding transverse annular shoulders z', anthe bores of the hub are shaped accordingly. The blades and their journals are made from wood.

- For assembling the propeller the shafts or journals e'and f are placed rinto-the recesses oforfe of the sections ofthe hub, the other section and the capy p axrglplaced thereon, and the hub sections are fi y by means'of the screwbolts fm and n. Should it be desired to vary the position of the blades relatively tothe hub the screws m and n areA pressed together i slightlyunscrewed and the blades are turned 85.

lnto the desired annular position, whereupon wardly for clamping the parts'together.

In the operation of the propeller the centhe 'screw bolts m' and n are agairrscrewed'intrifugal actionforces .the annular shoulders i of the journals or shafts e and f olnthe correspondmg annular shoulders formed in j the hub, the ,cylindrical portions c and d permitting'slight displacement of they journals axlallyof the blades, until the shoulders z' are 1n engagement withfthe/corresponding l shoulders ofthe huh.

-In the construction o f the propeller itl is dxtl'icult to manufacture the'reccsses of the llubandv the stepped portions of the journals of the blades exactly alike, and it may hap pen that onlyv some or only one of the cylindrical portions c and d of the journals are in engagement with the walls of the recesses of the hub, so that the number of the supporting surfaces of the'hub is reduced andlthe surface pressure of the said portions vis too high. To insure exact fittingof the surfaces c and al being raised Iinto the same by the edges of the sectional hubs, or the journals may be made with stepped cylindrical surfaces which are larger in diameter than the recesses' of the ,/hub, and IWhich are brought into nal shape by turning the same wit in the recesses, the edges of the recesses acting as frais'rng tools. Thereby an exact fitting of the parts and a uniform distribution of the forces are insured. -A

" I claim:

1. A propeller foraircraft,.comprising a Wooden blade formed at its inner end with a journal tapering from its end towards the' body of the blade andcomposed of a plurality of stepped cylindrical portions' bounded at theiradjacent ends by transverse annular shoulders perpendicular to the` axis of said journal, and ahub formed with a borelcorr'esponding in shape to the shape of the ournal and having said'journal mounted therein.

perpendicular to the axis of said journal.

signature.

therein, said hub being ydivided axiallyy of the bore into sections' and the sections of the bore thus produced being formed with sharp edges. Y

4. A propeller blade comprising a bodyand a journal of wood tapering from its end towards said body and, composed of stepped cylindrical portions bounded at their'adjacent ends by transverse annular shoulders 5. A hub comprising a body and a tapering bore composed of stepped cylindrical portions bounded 'at their adjacentends by transverse annular shoulders perpendicular to the axis of said bore. I ,80

' In testimony whereof I hereunto a-iix my j HEINRICH sUKoHL.

2. A propeller for air-craft, comprising a Wooden blade formed at its inner end with a journal tapering from its end towards the ylas Vyvooden blade formed at its inner end wit journal. tapering from its end towards the body of the vblade and composed of a plurality of stepped cylindrical portions bounded at their adjacent ends by transverse annular shoulders perpendicular to the axis of said journal, a hub vformed with a ybore correj sponding in shape to the shape of thejournal and having said journal mounted therein,

fsaid hub being divided axially of the bore -intosections, and means for clamping said sections and the journal embedded therein together.

3. A propeller for air-craft, comprising av a body of the 'blade and composed of a plurality of stepped cylindrical portions bounded at their adjacent ends by transverse annular shoulders perpendicular to the axis of said journal, a vhub formed witha bore A correspondin in shapeto. the shape of the journal and aving said journal mounted 

